Computing instrument



Jan. 7, 1947, E. P. oss EI'AL (EOMPUTING INSTRUMENT Original FiledMarch- 31, 1932 IN VENT ORS S. Marsh 'Ellzott P Boss Harcy fin? TTORNEYSPatented .lan. 7, 1947 COMPUTING INSTRUMENT Application March 31, 1932,serial No. 602,375 Renewed June 18, 1936 '7 Claims.

This invention relates to computing instruments and more particularly toinstruments for computing values of quantities which vary with respectto other quantities, such for instance as ballistic data relating tofire control problems. In such cases the quantities to be determinedusually vary non-uniformly from a straight line plotted with respect tocoordinate axes.

It is an object of the invention to produce an instrument of simpleconstruction for obtaining directly without modification the correctvalues of the required quantities by algebraically combining the amountsby which they vary from an assumed straight line or linear function withthe values of such assumed linear function.

In general the instrument consists of a plurality of simple cams thecontour of each of which is based on a different value of a factor ofwhich the required quantity is a function, the radial distances from thecenter of the cams to their peripheries representing the exact values ofthe differences between the required quantity and for linear values ofthe assumed straight line function. Cooperating with these cams is afollower which may be brought, by suitable shifting mechanism, intocoacting relation with the proper cam to compute the required quantityat the hosen value of the factor. The displacements of the follower aretransmitted, preferably by m ans of a follow-up mechanism, to a devicewhere they are combined with the corresponding values of the assumedstraight line function to give the required corrected values of thequantity. The instrument also includes means for rendering the transmiting mechanism inoperative durthe shifting of the follower from one camto another and means for locking the follower shiting mechanism againstaccidental motion in each position of adjustment of the followerrelative to the cams. This latter means also serves to indicate to theoperator of the instrument when the follower is in proper coactingrelation with any one of the cams.

lhe particular nature of the invention as well as other objects andadvantages thereof will appear most clearly from a description of a preferred embodiment thereof as shown in a diagrammatic manner in thesingle figure of. the drawing. For purposes of illustration theinvention has been embodied in an instrument for computing the sightdepression, that is, the elevation of the gun above the line of sightrequired for the trajectory of its projectile.

The instrument shown is adapted to compute the sight depression for anyone of three predetermined values of initial velocity of the projectile.It is of course obvious, as will appear hereinafter, that the instrumentmay be arranged to compute the sight depression for any one of a greateror lesser number of predetermined values of initial velocity.

The initial velocity at which the projectiles are to leave the gun orguns is communicated to the operator at the instrument who will set theinstrument for computation at this value of the initial velocity bybringing the proper sight depression cam into operational engagementwith the computing mechanism of the instrument. This is done by turningthe initial velocity crank l, mounted on shaft 2, until the chosen valueof the initial velocity is indicated on dial 3 opposite index 4. Dial 3is driven by shaft 2 through a pinion 5 mounted thereon which mesheswith a speed reducing gear train 6 on the output shaft of which dial 3is mounted. The speed reducing gear train is such that the dial willmake but a fraction of a revolution for a plurality of revolutions ofshaft 2. Shaft 2 is mounted for rotation in a frame member 5 and carriesbetween this member and crank I an elongated screw 8 coaxial therewith.In engagement with screw 8 is a forked nut 9 between the prongs of whichis pivoted a cam follower arm l8 slidably mounted on guides l l of aframe member :2 which is supported for rotation by shafts l3 and i lpivoted at different points in frame member 7.

Cam follower arm it carries two cam followers l5 and I6 rotativelymounted thereon. These followers are so located as to enable one or theother of them to follow sight depression cams of markedly differentcontours. The followers are placed on different sides of the followerarm and are so spaced therefrom that when one is in following contactwith one of the sight depression cams the other will be out of the pathof the adjoining cam. These sight depression cams are designated ii, isand I 9, and are coaxially arranged on a shaft as to be rotatedtherewith. The contour of each cam is different and is based on adifferent value of theinitlal velocity. The values of the initialvelocity upon which the cams are based are scribed on the face of dial3. Shaft 2 terminates in a pinion 2i which drives a speed reducing geartrain 22 to which is connected by means of shaft 23 the heart shaped cam24. A cam follower 25 carried by an arm 26 fixed to the end of shaft i3is positioned in the plane of the heart cam 26.

As shaft 2 is rotated during the change of setting of the instrument,nut 9 will be carried along the axis of screw 8 and will cause followerarm if! to slide on guides ll of frame l2 to carry cam follower H5 or itout of contact with the cam corresponding to the last setting and intoposition to co-act with the cam corresponding to the new setting. Due tothe shape and arrangement of cam follower arm If) it is necessary toswing it out of the Way of the cams to avoid interference during thechange of setting. This is accomplished as shaft 2 rotates by therotation of pinion 2!, speed reducing gear train 22, and shaft 23 whichrotate heart cam 25. As cam 24 rotates, in either direction, it willoffer to the contact of cam follower 25 a radius greater than thatoffered in the position shown in the drawing. This causes cam follower25, arm 25, shafts l3 and i l, frame l2 and follower arm H] to rotate ina direction to carry arm l5 and cam followers l5 and I5 out Of the wayof cams ll, :8 and i9. The ratio of the speed reducing gear train 22 issuch that the cam 25 makes one revolution for each change of position ofarm It from one cam to the next due to the rotation of shaft 2. As thecam 24 nears the end of each setting movement the slope of the campermits the arm 26 to rotate in the reverse direction so that when theend of the setting period is reached the follower 25 is opposite thenotch of cam 25 and one of the cam followers l5 and IS on the followerarm i is aligned with and free to follow the contour of the selected camH, it or I9.

Assuming that the drawing represents the condition of the instrumentafter it has been adjusted to compute the sight depression at the valueof the initial velocity communicated to the operator, and that theoperator has also received the range of the target, the operator willthen rotate range crank 2'! carried at the end of shaft 20 until thedesired value of the range is indicated on dial 28 opposite index 29,dial 28 being driven from shaft 26 through a speed reducing gear train55. The rotation of shaft 20 will through bevel gears 3|, shaft 32 andbevel gears 33 cause a like rotation of shaft 34 upon which is fixed apinion of a gear train 35 which terminate in a pinion 35 in mesh with agear 31 forming an integral part of the side 38 of differential 38. Geartrain 35 converts the rotation due to the range input into a rotationwhich is equivalent to the linear value of the assumed straight linefunction of the sight depression corresponding to the range input. Sincethe center 38" of the differential 353 is connected to a train ofelements which for the present can be considered as holding it againstrotation, the rotation of side 33 will be transmitted to side 38" tocause the rotation of gear 59 integral therewith.

As shaft 20 is rotated, cams l'f, l8 and 19 will also be rotated and cam11, in this instance, will offer a radius to the contact of cam followerl which is equivalent to the amount by which the sight depression curvediffers from the straight line function of the sight depression at theinput value of the range. Movement of follower arm Hi through frame l2causes a corresponding rotation of shafts l3 and I l. The movement ofshaft I4 is transmitted through gear sector 40 carried fixed thereto, toa pinion 48 mounted on shaft 52. A spring d5 connected to the frame ofthe instrument and the gear sector 45 serves, through gear sector 55,shaft Is, frame l2, and follower arm if to hold cam follower H3 or inconstant contact with the face of cam H, is or I9 except when thefollowers l5 and iii are forcibly held out of contact with cams H, [8 orIE by the cam and the arm 25 during the operation of shifting from onecam to another. The rotation of shaft 42 is transmitted through bevelgears 43, shaft 55, bevel gears 45 and shaft G6 to a gear 41 whichmeshes with a gear pinion 43 fixed to shaft 39 which carries the center38" of the differential 38.

Considering now side 38' as fixed, center 38" will rotate side 58 inaccordanc with the value of the difference between the sight depressioncurve and the straight line function of the sight depression at therange input value and will algebraically combin this value with thevalue of the straight line function set into the differential by thepreviously described rotation of side 38 so that the net rotation ofside 38" and gear will be equal to the corrected value of the sightdepression at the input range value. Gear 39 meshes with gear 55 whichis an integral part of side 5i of differential 5|. Since side 5|" mayfor the present be considered as fixed, side 5| will rotate center 5|and shaft 52 upon which the center 5l' is fixed.

Shaft 52 carries at its end a cam 53 on the surface of which bears a camfollower 54 carried by a lever 55 pivoted on a pin 55 fixed to the frameof the instrument. A spring 5'? having one end fixed to the instrumentframe and the other end to lever 55 serves to hold cam follower 54 inconstant contact with cam 53. Lever 55 carries at its other end andinsulated therefrom a double contact arm 58 having contacts 59 and 58adapted to contact with fixed contacts GI and 62 respectively uponproper movement of lever Contact arm 58 is connected through conductor53, cutout switch 64 and conductor 65 to the plus side of the D. C.supply lin 66. A conductor 5'? connects fixed contact 6| to one of thefield terminals of reversible D. C. servo motor 63, the other fieldterminal of the motor being connected through conductor 69 to the fixedcontact 62. The armature terminal of the motor is connected throughconductor 10 to the minus side of the D. C. supply line 66. a

As shaft 52 rotates in response to the computed value of the sightdepression, cam 53 will rotate therewith and will displace cam follower54 from its normal position on the slope of the cam 53. Thisdisplacement of cam follower 54 will cause lever 55 and contact arm 58to move about pivot 55 to carry one or the other of the contacts 59 andinto contact with its respective fixed contact, thereby closing theelectric circuit and energizing motor 68. The rotation of motor 68 istransmitted through pinion H and speed reducing gear train 12 to shaft13 which carries a dial "M upon which, opposite index 15, may be readthe computed value of the sight depression. Rotation of shaft 13 willthrough bevel gears 16 and shaft TI cause gear 58 to rotate. Gear 18meshes with gear 79 which is integral with side 5| of differential 5|,and since side 5! may temporarily be considered as fixed, rotation ofside 5|" under the action of motor 68 will rotate center 5| and shaft 52to algebraically combine the previously described rotation of side 5|with the rotation of side 5|.

When the algebraic rotation of shaft 13 and gear 55 are equal orequivalent, the sum of the rotations applied to shaft 52 is zero, andshaft 52 will have carried cam 53 and contact arm 58 back to theposition shown in the drawing and motor will have been deenergized. If,for any reason, the rotation of shaft 52 is reversed due to reversal ofrotation of side 5 I or the rotation of side 5|" due to motor 68 exceedsthe rotation of side 55', then the arm 58 will be moved to reverse thedirection of rotation of motor 68. The motor will run in this directionuntil the sum of the rotation is zero when its circuit will be opened bycontact arm 58 moving back to the open circuit position. The action ofthe motor 68 is very rapid and the motor will respond to and remove eachincrement of movement of shaft 52 with the result that cam follower 54will never be very far from its normal position on the slope of the cam.

In the preferred embodiment the follow-up mechanism has been shown anddescribed as including a reversible D. C. motor 68, but the invention isnot limited to the use such motor as a reversible A. C. motor or otherreversible electrically operated rotation generating means may equallywell be used.

The instrument is provided with a detent mechanism to lock shaft 2against accidental motion in each of the positions of arm 40 relative tocams It, i 8 and 19. The detent mechanism also serves as a means forfacilitating the bringing of follower arm iii and the cam followers l5and !6 in exactly the proper positions relative to cams I1, 58, 99. Thisdetent mechanism comprises two notched discs 86 and 31 into the notchesof which rollers 82 and 83, carried by a Y shaped lever 8 5 pivoted on apin 85 fixed to the frame of the instrument, are adapted to be held bythe force exerted by spring 86 which has one end connected to lever 84and the other end to the frame of the instrument. Disc 80 is mounted onshaft 87 to rotate therewith and disc Si is carried by a collar 88concentric with shaft 8! but of such size as to be freely rotatablethereon. To collar 83 is also fixed a gear 89 which forms part of thespeed reducing gear train 90 driven from shaft 8? by pinion 9i. Shaft 87is driven by shaft 2 through bevel gears 92. Speed reducing gear train9%] is so arranged that disc 8i will make but one revolution during eachchange of position of follower arm Ii).

Assuming that the elements of the instrument are positioned as shown inthe drawing and it is desired to carry cam follower i6 into contact withcam l8. exert suficient force at crank i to overcome the force of spring85 which tends to hold rollers 82 and 58 in the notches of discs 88 and8!. As shaft 2 rotates shaft 8'! through bevel gears 92, the roller 82will be carried out of the notch of disc 89 and will be caused to bearagainst the normal periphery of the disc Bil. The force required atcrank i to rotate shaft 2 will then be diminished since the rollers 82and 83 are no longer embraced by the notches in the discs. When disc 38has almost completed one revolution the notch of disc 8.! will be out ofline with roller 83 and roller 83 will be in contact with the normalperiphery of this disc until within a revolution of shaft 2 from the endof the adjustment movement thereof when the notch of disc 8| will beginto align itself with roller 83. At this time however the normalperiphery of disc 80 will be ofifered to contact with roller 82 andlatching prevented until the time when both notches are aligned withtheir respective cooperating rollers. This will occur at exactly thetime when arm Ill and cam follower it are properly located relative tocam 18. At this time the .force necessary to move crank I will suddenlyThe operator will initially have to r 6 increase and the operator willthus be made aware that the adjustment is completed.

Since the instrument includes an electric motor the circuit controlmechanism of which is affected by the movement of the elements abovedescribed a cut-out switch 64 is provided to render it impossible toenergize the circuit of the motor during the change of position offollowerarm I ll. This switch 64 has a fixed contact member 93 which isconnected through conductor 63 to contact arm 58 of the motor circuitcontrol mechanism, and a movable spring contact member 94 which isconnected through a conductor 65 to the plus side of a D. C. supply line66. Thus when contact members 93 and 94 are separated the motor cannotbe energized. To separate the contact members a lever 95 pivoted on pin96 fastened to the frame of the instrument is provided. One end of thelever is normally maintained away from contact member 94 by a spring 97which has one end fastened to the frame of the instrument and the otherend fastened to this end of the lever. Spring 91 also serves to keep theother end of the lever 95 in contact with a notched disc 98 which isdriven by shaft 2 and pinion 5 through a speed 'reducing gear train 99.The gear train is such that disc 98 will make one revolution during eachchange of position of follower arm ii) relative to the cams. As shaft 2begin to rotate the end of lever 95 which is in contact with disc 98will be carried out of the notch and onto th normal periphery of thedisc. This will cause lever '95 to move about its pivot so that the endwhich cooperates with spring contact member 96 will come in contacttherewith and will carry it away from contact member 93. When theadjustment is completed disc 93 will again offer the notch to thecontact of lever 95, thus allowing spring 91 to carry the lever 95 outof contact with the spring contact member 9a to allow contact springmember 9:3 to again contact with contact member 33.

While a preferred embodiment of the invention has been shown anddescribed it Will be understood that the invention may be embodied inother forms and various changes may be made in structural detailsWithout departing from its principle as defined in the appended claims.

We claim: I

1. In an instrument for computing the value of a quantity which varieswith respect to another quantity, the combination of a member, quantityconverting means for displacing the member in accordance with an assumedvalue of the first quantity with respect to the second quantity, aplurality of separate devices each representing .the amount by which thefirst quantity dilfers from the assumed value for a predetermined valueof a factor affecting the values of the first quantity for anyparticular value of the second quantity, means for displacing thedevices in accordance with the value of the second quantity, an elementadapted to co-act with the devices one at time, means for shifting theelement into co-acting relation with any desired one of the devices inaccordance with the predetermined values of the factor, a second memberoperable by said element and means for combining the resultantdisplacements of the members.

2. In an instrument for computing the value of a quantity which varieswith respect to another quantity, the combination of a member, quantityconverting means for displacing the member in accordance with an assumedvalue of the first quantity with respect to the second quantity, aplurality of separate devices each representing the amount by which thefirst quantity differs from the assumed value for a predetermined valueof a factor affecting the values of the first quantity for anyparticular value of the second quantity, means for displacing thedevices in accordance with the value of the second quantity, an elementadapted to co-act with the devices one at a time, means for shifting theelement into co-acting relation with any desired one of the devices inaccordance with the predetermined values of the factor, a second memberoperable by said element, means for combining the resultantdisplacements of the members, power operated indicating means forindicating said resultant displacements and means effective while theelement is being moved from one to another of the devices to render theindicating means uninfluenced during the displacement of the element.

3. In a computing device a plurality of spaced cams, a shaft mountingsaid cams, a cam follower element, a pivoted carriage mounting saidfollower element for rotation therewith, said follower element beingmovable longitudinally independently of said carriage, trunnions forsaid carriage, a second shaft, an elongated screw mounted thereon, a nuton said screw operatively connected to said follower element to movesaid follower longitudinally of said carriage whereby said followerelement may be brought into operative relation with any desired one ofsaid cams to be displaceable thereby, a second follower element mountedon one of said trunnions to move therewith, a cam co-operating with saidsecond follower element, and means connecting said last mentioned camwith said second shaft whereby as said second shaft is rotated to movesaid first mentioned follower element from one to another of saidplurality of cams said last mentioned cam displaces said secondmentioned follower element to move said first mentioned follower elementaway from said plurality of cams and to allow said follower element tocome back into displacing relation when said follower element is againaligned with one of said plurality of cams.

4. In a computing device a plurality of spaced cams, a shaft mountingsaid cams, a cam follower element, a pivoted carriage mounting saidfollower element for rotation therewith, said follower element beingmovable longitudinally independently of said carriage, a second shaft,an elongated screw mounted thereon, a nut on said screw operativelyconnected to said follower element to move said follower longitudinallyof said carriage whereby said follower element may be brought intoco-operative relation with any desired one of said cams to bedisplaceable thereby, a second follower element rigid with said carriageto move therewith as it is rotatively actuated, a cam co-operating withsaid second follower element, and means connecting said last mentionedcam with said second shaft for actuation thereby to operate said secondfollower element and carriage whereby the first mentioned followerelement is displaced to clear said cams as it is moved longitudinally ofsaid carriage.

5. In a computing device a plurality of spaced cams, a shaft mountingsaid cams, a cam follower element, a pivoted carriage mounting saidfollower element for rotation therewith, said follower element beingmovable longitudinally relative to said carriage, trunnions for saidcarriage, a second shaft, an elongated screw mounted thereon, a nut onsaid screw operatively connected to said follower element to move saidfollower element longitudinally of said carriage whereby said followerelement may be brought into cooperative relation with any desired one ofsaid cams to be displaceable thereby, a differential having a pluralityof input elements and an output element, means connecting said firstshaft to one of the input elements, means connecting one of saidtrunnions to another input element, a second differential having aplurality of input elements and an output element, means connecting oneof the input elements of the second differential with the output elementof the first differential, an electric motor, a value indicating meansoperated thereby, a motor control means, and means connecting said valueindicating means to another input element of the second differential.

6. In a computing device, a plurality of predeterminedly spaced axiallyaligned cams, means for turning said cams, a cam follower, meansincluding a rotatable element for moving said cam follower axially ofsaid cams to a selected one thereof, and governing means connected withsaid rotatable element comprising members rotatable at different speedsto periodically come into positional agreement at times when said camfollower is in cooperative relationship with one or another of said camsand latching means effectively co-acting with said members only whenthey are in positional agreement thereby restraining said rotatableelement and maintaining said cam follower in alignment with the selected7. In a computing instrument, the combination of a plurality of axiallyaligned rotatable cams, a pivoted frame, a cam follower movably mountedon the frame, means for axially moving the follower with respect to theframe into engageable relation with any one of the cams, meansassociated with the moving means for maintaining such engageablerelation at predetermined positions of the moving means, means forrotating the cams to cause displacement of the follower and the frame onwhich it is mounted and means associated with the moving means forturning the frame to displace the follower angularly out of the path ofthe cams while it is being moved from one cam to another.

ELLIOTT P. ROSS. HARRY S. MARSH.

